(a) Field of the Invention
The present invention relates to a method and an apparatus for controlling an operation voltage of a processor core, and a processor system including the same.
(b) Description of the Related Art
A processor core reads instructions stored in a storage unit such as a memory or a disk, performs a specific operation depending on an operation encoded in the instructions, and stores a performance result. That is, the processor core is hardware or intellectual property (IP) executing an algorithm for a specific application area.
An application area of the processor core has been widely applied over all system semiconductor fields. An application area of the processor core has been applied to various areas such as high performance media data processing for large-capacity multimedia data, a minimum performance micro-controller platform, an apparatus to which power may not be stably supplied or to which power may not be supplied from the outside, and the like. As the large-capacity multimedia data, there are video data compression and decompression, audio data modification, sound effects, and the like. As the minimum performance micro-controller platform, there are a wired/wireless communication modem, a voice codec algorithm, network data processing, a touch screen, a home appliance controller, a motor control, and the like. As the apparatus to which power may not be stably supplied or to which power may not be supplied from the outside, there are a wireless sensor network, tiny electronic devices, and the like.
The processor core includes an instruction execution logic, a translation lookaside buffer (TLB), and a cache memory. A task to be executed by the instruction execution logic is composed of a combination of a plurality of instructions. That is, the instructions are stored in the memory and are sequentially input to the instruction execution logic, and the instruction execution logic performs a specific calculation per clock period. The TLB serves to convert a virtual address into a physical address in order to drive an operating system based application. The cache memory temporarily stores instructions stored in an external memory in a chip (chip of the processor core) to increase a speed of the processor core.
Power consumption of the processor core is configured of dynamic power consumption and static power consumption. The dynamic power consumption Pdynamic is represented by Pdynamic=αfcVdd2. Here, α indicates a switching probability, f indicates an operation frequency, c indicates a switching capacitance, and Vdd indicates an operation voltage. The static power consumption Pstatic is represented by Pstatic=Istatic Vdd. Here, Istatic indicates an average current that flows statically. Both of the dynamic power consumption and the static power consumption are decreased as the operation voltage is decreased. Particularly, the dynamic power consumption is more rapidly decreased when the operation voltage is decreased.
Meanwhile, when the operation voltage is decreased, an operation frequency of the processor core is also decreased, such that performance may be decreased. However, generally, the performance is linearly decreased, while the dynamic power consumption is exponentially decreased. Therefore, when the operation voltage is decreased, power efficiency (power consumption per unit frequency) is increased. Particularly, in a sensor application requiring a long operation time, it is an important factor of a design to decrease the power consumption.
As described above, it is important to decrease the operation voltage in order to decrease the power consumption. However, in the case of a processor core configured of a complementary metal oxide semiconductor (CMOS), when an operation voltage is decreased to a predetermined voltage or less, a circuit may not be appropriately operated. That is, an operation voltage margin is not sufficient, such that normal operation of the circuit may be impossible. In addition, since a minimum voltage at which any circuit may be operated is changed depending on current consumption, a temperature, and characteristics when a chip is manufactured, there is a problem that it is difficult to determine a minimum voltage value after the chip is designed.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.